1. Field of the Invention
The present invention relates to a circuit structure, and more particularly to a redistribution circuit structure and manufacturing method thereof.
2. Description of Related Art
With the rapid development in the electronics industry, semiconductors are adopted everywhere. In response to the requirements in the electronics industry, many types of techniques related to the semiconductor process are also rapidly developed. In general, semiconductor processes can be roughly divided into front-end processes and back-end processes. The front-end processes include the formation of a semiconductor substrate such as silicon growth and epitaxial growth and the fabrication of semiconductor devices such as metal oxide semiconductor (MOS) and multi-layered metal interconnections. The back-end processes include the packaging process for protecting the chips, preventing moisture from getting to the chips and avoiding damage by external forces. Furthermore, the connection points on the package body permits electrical connection of the chips with electronic devices outside the package.
Packages can be roughly classified into wire bond (WB) process, tape automatic bonding (TAB) and flip chip (FC) process. The wire bond process is one of the more fully developed techniques and is a widely used technique in many types of electronic packages. In the wire bond process, conductive wires are used to connect contacts on a chip with contacts on a carrier so that the chip may transmit electrical signals to the external. The carrier is a package substrate or a lead frame, for example. In general, the connection points of the chip are disposed not too far away from the contacts of the carrier to facilitate the wire bonding process. However, due to changes in the locations of the contacts of the carrier or in response to the requirements of a different product, the distance between the connection points of the chip and the contacts of the carrier may be too long. As a result, the strength of conductive wires may be low or other electrical problems due to the long conductive wires may emerge. Thus, redistribution process has to be applied to change the circuit layout of the external contacts on the chip. It should be noted that an auxiliary bonding force has to be applied in the wire bonding process. Hence, the area underneath the pads needs to hold out against substantial impact energy. Therefore, electronic components are normally not disposed underneath the pads to prevent the image energy from damaging those devices. Yet, the area of the chip is increased due to the redistribution.